Heat transfer system



Jan. 23, 1940. "F. H. BREHOB 2,183,172

HEAT TRANSFER SYSTEM Fil ed Jan. 6, 1937 Inventor";

Fj'rgjedevigLiflH. Zr'ehob, bg W His Attorney.

Patented Jan. 23, 1940 UNITED STATES PATENT OFFICE eral Electric Company,

York

a corporation of New Application January 6, 1937, Serial No. 119,277 7 9 Claims.

The present invention relates to. an improved heat transfer or attemperating system particularly useful in'maintaining the lubricating and cooling media of a prime mover or other mechanical apparatus at desired temperatures.

In the operation of certain types of prime movers of the internal combustion variety it is required to maintain the oil at a relatively low temperature and to circulate it at relatively high pressure. In the cases where this is true, great difficulty is experienced in providing a satisfactory cooling system. Inparticular, the requirement of high pressure makes the construction of a satisfactory air-cooled radiator substantially 1i impracticable because of the relatively great wall thickness and round tube shape needed to withstand the internal stresses created. It will be readily understood that both these factors are incompatible with effective heat release and radiation.

A particular object of the present invention is to provide an improved method and means of heat transfer whereby this difiiculty may be substantially overcome. In accordance with a preferred embodiment of the invention, this is accomplished by cooling the oil through heat exchange with a portion of the engine cooling water, which portion has been brought to a temperature appreciably below the desired average cooling water temperature. As will be explained more fully hereinafter, this mode of procedure permits the use of a combined oil and water cooling system which is compact, of light weight, and highly emcient in operation.

The features of novelty which I desire to protect herein are pointed out with particularity in the appended claims. The invention itself, together with .further objects and advantages thereof, will be best understood by reference to the following description taken in connection with the accompanying drawing, in which the single figure represents a prime mover combined with an oil and water cooling system suitably embodying the invention.

Referring to the drawing there is shown a prime mover, which is indicated as being of the Diesel engine type and which comprises a casing including a cylinder block l0 and a crank case H. Associated with the crank case portion there are provided connections or conduits l3 and M for circulating oil back and forth between the crank case and an oil cooling device. Oil circulation is maintained, for example, by means of a pump l6 interposed between the crank case outlet and the oil cooler. If the bearings of the Diesel engine are of the forced lubrication type, as is generally the case, the pump l6 must be capable of developing a considerable pressure, say on the order of pounds per square inch. This means that the remainder of the oil-circu- 5 lating system-must have sufiicient mechanical strength to withstand such a pressure and that the cooling device in particular must have walls of suflicient thickness and proper shape to prevent rupture. In accordance with the present 10 invention this last condition is fulfilled without an undue sacrifice of efliciency by making the oil cooling device a part of a heat exchanger which comprises, for example, an oil circulating coil l8 and an enclosing casing l9 for receiving 15 water from the cooling system of the prime mover. Due to the relatively eflicient heat transfer which takes place in a liquid to liquid cooling system, it is possible to use a much greater wall thickness for the coil is than would be per- 20 missible if this coil were to comprise simply an air-cooled radiator.

In the operation of a Diesel engine it is generally expedient to maintain the cooling water at a temperature appreciably above that at which 25 the oil supply is to be held. Therefore. in order to avoid the necessity for reducing all of the circulating water to a low temperature simply for the purpose of cooling the oil, it is preferred to employ only a portion of the cooling water for 30 this purpose. This may be accomplished by utilizing for the water cooling system an attemperating device, for example, an air-cooled radiator, having separate portions A and B, of which the former is constructed and arranged to operate at 35 a lower temperature than the latter. In the particular arrangement which I have illustrated in the drawing the radiator comprises a single inlet header 23 connected with the prime mover by a conduit l5 and a pair of separate outlet headers 24 and 25, these headers being joined by cooling tubes which constitute the separate radiator portions. In order to cause the water which issues from the header 24 to be at a lower temperature than that flowing from the header 45 25, various expedients are possible as, for example, making the flow impedance of radiator portion A greater than that of radiator portion B so that the water passes more slowly through the former. With this arrangement, augumenteri if necessary by the provision of extended cooling surfaces for the radiatorportion A, it is readily possible to cause the water in that portion to be cooled down as low as F., for example, while the water flowing through the radiator portion B 55 needs to be cooled only to a temperature slightly above that desired to be maintained at the cylinder block inlet. Subsequent admixture ofthe high and low temperature components may be relied upon to bring the average temperature to the desired value which may be as high as 175 F.

The water flowing from the header 24 may be led through a conduit or connection 29 to the heat exchanger casing l9 where it passes in counterflow to the hot oil flowing through the coil l8. The dimensions of the heat exchanger as a whole may be such that if the entering oil temperature is about 150 F., its leaving temperature will be about 140 F., whereas the water which enters at about 130 F. will leave at a higher value, say 135 F.

The cooling Water may be forced through the prime mover by means of a common conduit or connection 32 and a common circulating pump 33. The connection from the radiator portion A to this common conduit includes the heat exchanger casing I9, while the connection from the radiator portion B comprises a conduit 35. The relative amounts of water flowing through the respective radiator portions may be varied by changing the relation of their flow impedances as, for example, by means of regulating valves interposed in their flow connections. In the present case, I have illustrated a manually adjustable valve 36 as being included in the conduit 35 which connects the radiator B with the common return conduit 32.

In applications such as in locomotives or similar self-propelled vehicles where economy of space is essential the cooling system described in the foregoing presents numerous advantages. Since the oil is cooled indirectly rather than by exposure to a moving air stream, the oil heat exchanger can be made simple and compact and can be so located that the pipe lines to and from the engine may b made very short and inexpensive to install. Furthermore, since both radiator portions A and B carry the same liquid, namely, water at a low pressure, they can be made of generally similar construction and can be combined into a single structure if desired. Inasmuch as only a portion of the water is required to be cooled below the desired oil temperature, the radiator as a whole need have a suflicient capacity only to reduce the average water temperature to approximately the desired value.

While I have described my invention in connection with particular structures-it will be understood that many modifications may be made by those skilled in the art without departing from the invention. 1, therefore, aim in the following claims to cover all such modifications as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination. an apparatus including oil and cooling water circulating systems, a heat exchanger. means for conducting oil back and forth between the heat exchanger and the apparatus, a radiator comprising a single inlet header and a pair of outlet headers, the connections between said headers forming separate radiator portions of which one is constructed and arranged to operat at a lower temperature than the other, means for conducting water from the apparatus to the radiator inlet header, means for conducting Water from the outlet. header of the higher temperature radiator portion to th apparatus, and means for conducting water from the lower temperature radiator portion to the heat exchanger and thence to the apparatus.

2. In combination, a prime mover including oil and cooling water circulating systems, a heat exchanger, means for conducting oil back and forth between the heat exchanger and the prime mover, a radiator comprising a single inlet header and a pair of outlet headers, the connections between said headers forming separate radiator portions of which one is constructed and arranged to operate at a lower temperature than the other, means for conducting water from the prime mover to the radiator inlet header, a conduit for returning water from both radiator portions to the prime mover, connections including the heat exchanger for conducting water from the low temperatur radiator portion to the conduit, and connections for conducting Water directly from the high temperature radiator portion to the conduit.

3. In combination, a prime mover including oil and cooling water circulating systems, a heat exchanger, means including a pump for circulating oil back and forth between the heat exchanger and the prime mover, a cooling structure including a high temperature and a low temperature portion, means for conducting water from the prime mover to the cooling structure, means ineluding a conduit and pump for returning water to the prime mover from both portions of the cooling structure, connections including the heat exchanger for conducting water from the low temperature portion of the cooling structure to the conduit and connections for conducting water from the high temperature portion of the cooling structure to the conduit.

4. In combination, a prime mover including oil and cooling water circulating systems, a heat exchanger, means for conducting oil back and forth between the heat exchanger and the prime mover, a radiator comprising a single inlet header and a pair of outlet headers, the connections between said headers forming separate radiator portions of which one is constructed and arranged to operate at a lower temperature than the other, means for conducting Water from the prime mover to the radiator inlet header, a conduit for returning water to the prime mover, connections including the heat exchanger for conducting water from the outlet of the low temperature radiator portion to the conduit, connections for conducting water from the outlet of the high temperature radiator portion to the conduit, and means associated with one of the connections for regulating the relative rates of flow through the radiator portions.

5. In combination, an apparatus having separate circulating systems for a first and second fluids, each requiring to be regulated as to temperature, attemperating means in circuit with the circulating system for the first fluid and comprising two portions having different temperature of operation, means functioning continuously throughout the normal operation of the apparatus to supply ouantities of the first fluid from the apparatus to each portion of the attemperating means without passage through the other portion, means for bringing the second fluid into heatexchanging relation with the part of the first fluid issuing from one portion of the attemperating means, and means for returning to the apparatus said second fluid and substantially all the first fluid issuing from both portions of the attemperatin'g means.

6. In combination, an apparatus having lubricating and cooling fluid circulating systems associated therewith, attemperating means in circuit with the cooling fluid circulating system and including a high temperature portion and a low temperature portion, means functioning throughout the normal operation of the apparatus to supply cooling fluid from the apparatus to each portion of the attemperating means without passage through the other portion, means in circuit with the lubricating fluid circulating system for bringing the lubricating fluid into heat-exchanging relation with a part of the cooling fluid after passage thereof through the low temperature portion of the attemperating means, and means for returning to the apparatus substantially all the cooling fluid issuing from both portions of the attemperating means.

7. In combination, an apparatus having lubricating and cooling fluid circulating systems asso-- ciated therewith, attemperating means in circuit with the cooling fluid and including two radiator portions, one of which is constructed and arranged to operate at a lower temperature than the other, means efiective to supply cooling fluid from the apparatus directly to each radiator portion throughout the normal operation of the apparatus, means in circuit with the lubricating fluid circulating system for bringing the lubricating fluid into heat-exchanging relation with the cooling fluid issuing from the lower temperature radiator portion, and means for returning to the apparatus substantially all the cooling fluid issuing from both radiator portions.

8. A system for maintaining the lubricating oil and cooling water of a prime mover at desired temperatures, which system comprises means for withdrawing hot oil and water from the prime mover, means for cooling separate portions of the water thus withdrawn to difierent temperatures, means for cooling the hot oil by heat exchange with the cooler portion of water, means for recombining the differently attemperated portions of Water, and means for returning both portions of water and the cooled oil to the prime mover.

9. A system for maintaining the lubricating oil and cooling water of a prime mover at desired temperatures, which system comprises means for withdrawing hot oil and water from the prime mover, means for cooling a portion of the water below the desired temperature of the oil and the remainder to a higher temperature at least as high as the desired Water temperature, means for cooling the hot oil to approximately its desired temperature by heat-exchange with the cooler portion of water, means for combining the two portions of water and for returning both portions of water to the prime mover, and means for returning the cooled oil to the prime mover.

FREDERICK H. BREHOB. so 

